Method of and apparatus for performing looping on a multineedle seam covering sewing machine



Sept. 26, 1939. F. EBERT 2,174,205

METHOD OF AND APPARATUS FOR PERFORMING LOOPING ON A I MULTINEEDLE SEAM COVERING SEWING MACHINE Filed Aug. 4, 1936 4 Sheets-Sheet 1 2,174,205 M6 on A F. EBERT METHOD OF AND APPARATUS FOR PERFORMING LOOPI MULTINEEDLE SEAM COVERING SEWING MACHINE Filed Aug. 4. 1936 Sept. 26, 1939.

4 Sheets-Sheet 2 m i lg IWvem Z'Zr FFL'Z 568/?- M W Afforwey Sept. 26, 1939.

2,1 74,205 OPING ON A WING MACHINE 1956 4 Sheets-Sheet 3 F. EBERT ATUS FOR PERFORMING L0 Filed Aug.

MULTINEEDLE SEAM COVERING SE METHOD OF AND APPAR Sept. 26, 1939. F. E t 2,174,205

METHOD OF AND APPARATUS FOR PERFORMING LOOPING ON A MULTINEEDLE SEAM COVERING SEWING MACHINE Filed Aug. 4, 1936 4 Sheets-Sheet 4 Patented Sept. 26, 1939 "ATE'NT OFFICE METHOD OF AND APPARATUS -FOR PER- FORMING LOOPING ON.A MULTINEEDLE "SEAMCOVERING SEWING"MACHINET Fritz Ebert,

Oberndorf-nn-the-Neckar,

Ger-

".many, assignor to Mauser-Werke 'Ar'Gn, ()berndorf-on-the-Neckar,

Germany, a. joint-stock company of Germany Application August 4, 1935, Serial No. 94,246 In Germany February'ZG, 1935 14 Claims.

This invention relates" to a method and also an apparatus enabling articles or pieces of work to i be sewn continuously in such fashion on a multiineedle seam covering sewing machine that loop- .5 .ing is also performed between the. pieces of work,

.i.:.e.,1at:points'where there is no material, so that a proper seam is produced immediately upon the introduction ofthe second or following piece of work.

The purpose of the invention is to provide fimeans 'IfOI" "adapting the length of the needle threaddrawn at any time, to the thickness of thematerial; so that also'in embroidering without material the correct length of the thread and therefore'a regular formation .of stitch is obtained.

The "actual stitches of the overlapping seam are-formed by the looper threadpwhereas the needle'threads for the purpose of connecting the stitches correctly with each other and hence loops: must be formed by the needle threads into which. the looper can enter. 4

.For'this'reasonthe needle threads upon downmovementof the needles are caught so that sufficientlength of thread is present to form these loops when the catching is stopped.

If'this place of'catching for the needle threads is fixed then always the same length of thread willbe-drawn without consideration whether the materialis thick or thin or whether any material is present on the stitch plate and below the pressure'foot. In other words it is as if the length of the thread were in reverse proportion to the requirements, because with thick material, that is when: more thread must be drawn because a great'erpart ofthethread length lies inside the unaterial thickness than in the case of thinner material, since the thread length is always the same,'the loops for the looperwill be smaller than in the case of thinner material or even when no material is present. Since however, the loop must have a minimum size, this minimum size must be determined by the thickest .material which is to be sewn and this length'in the case of. thinner material or when no material is present is much too great. Hence arises the possibility that the seam will not have suffilcient firmness because the thread is not drawn sufficiently tight. From this consideration it is seen that the length of thread-must not always remain the same but that the catchingof the needle threads must be eflected in such a manner that the length of thread shall correspond to the actual conditions so'that alwaysindepend- .fifig-ent ctr-whether thick ,or thin material or "even no material is under the pressure foot, the loop -WhiChilh looper has to enter must have the correct size.

For this reason it is proposed according to the invention to make the catching place for the :55 needle threads variable in such a manner that in \the case of thick material correspondently more thread is drawnthan with thin material or when no material is present, and this con stitutes the main feature of the invention.

According to the invention a finger is provided attached to the pressure foot rod and which thus effects upward and downward movement corresponding to the thickness of the material present. Therefore, corresponding to the thickness of the material the finger determining the place of catching will lie higher or lower and will draw off the necessary thread length required for the desired size of loop. The finger is also pivotable about thepressure foot rod in a horizontal planein order that, at the beginning of the down stroke of the needles it can be swung in close behind these inthe path. of the needle. threads, and upon .arrival of the needles in the lowest position, when w the looper again moves-forward, will again move .back in order that the needle threads may slide .ofi thelooper and --after.falling downwards can form loops. In order finally to take care of the differentneedle and thread thicknesses there is 30 provided a further. adjustment by means of which" the fingercan be approached more or less closely to the plane of the needlewhereby no change is made in its other. functioning. A feature of the inventionalso consists in the finger moving in.

a transverse slot in the pressure foot whereby the finger not only receives an exact guiding but is also given a support when the overlying thread is .drawn downwards. The finger'may thus be made comparatively thin. 40

Themethod according to the invention is illusrated in a possible form of embodiment in the accompanying drawings in conjunction with a sewing machine of the supporting arm type. It will be understood, however, that the invention.; 45 is not restricted to this form of embodiment or to sewing machines merely of this kind.

Fig. 1 is a perspective view of the sewing machine, in which only those parts have been shown which directly pertain to the invention.

Fig. :2 is a plan view of the looping device in whichthe finger has been advanced up to the middle needle.

Fig. 3 is an elevational view in vertical section.

:-.-Figs. 4 and :5. are similar elevational views in 1'55 vertical section before and after the downward movement of the needles.

Figs. 6 and 7 are a rear view and sectional plan view respectively of the drive.

Figs. 8 to 10 illustrate progressively the formation of the seam.

The sewing machine, in conjunction with which the method according to the application will be described, is assumed to be of the supporting arm type. The sewing .or stitching mechanism is of the usual kind, this also applying to the drive for the elements producing the seam. In the particular form of embodiment shown these elements comprise three needles I, the looper 3 operating in the arm 2 and the presser 4. The needles I guide the threads 5 and the looper 3 guides the thread 6.

The method according to the invention consists in the fact that the needle threads 5 upon the downward movement of the needles I are prevented from being drawn and also prevent the looper 3 from entering the needle thread loops. In the embodiment according to the invention, this is effected by means of a finger I, which is preferably comparatively thin and curved and may be resilient in itself, but may also be of other form. This finger I moves prior to the downward movement of the needles I behind the latter or between their path of movement and the needle threads 5, as shown more particularly in Figs. 4 and 8. Upon the downward movement of the needles I, the needle threads 5 are then held by the finger I, as shown in Figs. 5 and 9, so that the looper 3 is able to enter the needle thread loops 8, as shown in Fig. 10.

According to the invention a finger I is provided attached to the pressure foot rod 9 and which thus effects upward and downward movement corresponding to the thickness of the material present. Therefore, corresponding to the thickness of the material the finger I determining the place of catching will lie higher or lower and will draw off the necessary thread length required for the desired size of loop. The finger I is also pivotable about the pressure foot rod 9 in a horizontal plane in order that, at the beginning of the down stroke of the needles I it can be swung in close behind these in the path of the needle threads 5, and upon arrival of the needles I in the lowest position, when the looper 3 again moves forward, will again move back in order that the needle threads 5 may slide off the looper 3 and after falling downwards can form loops. In order finally to take care of the different needle and thread thicknesses there is provided a further adjustment by means of which the finger I can be approached more or less closely to the plane of the needles whereby no change is made in its other functioning. A feature of the invention also consists in the finger I moving in a transverse slot in the pressure foot 4 whereby the finger not only receives an exact guiding but is also given a support when the overlying thread is drawn downwards. The finger may thus be made comparatively thin.

The finger I may be controlled in desired fashion. In the form of embodiment shown it is mounted to be capable of rocking motion, viz., about the presser rod 9. For this purpose it is located on an arm In which rocks about the rod 9 and to which the rocking motion is imparted by the machine drive or the drive for the looper 3, so that a separate drive is not required.

For the operation of the finger 1 there is provided on the arm II, which rocks the transverse member l2 for controlling the looper 3, a second arm l3. This arm, through the medium of a ball and socket joint and lever 14, reciprocates a lever I5, which is mounted to oscillate on a pin I6. In an upwardly extending arm ll of lever l5 there is provided a radial slot l8, in which there may be adjusted radially a bolt H! which forms the head of a connecting rod 20 that engages on the other hand with a bolt 2| located on the finger arm l0.

In this manner the finger I is caused to swing in and out by reason of the oscillation of the shaft 12 of the looper drive.

For the purpose of being able to vary the basic position of the finger I the connecting rod 20 is furnished with a left and right hand thread 22, so that the position of the finger I may be varied by turning the rod 20.

Provision is also made for adjustment of the finger I in accordance with the thickness of the particular thread or needles employed. For this purpose the arm I is not mounted in direct fashion on the presser rod 9, but on an eccentric sleeve 23 which may be turned on the rod 9 and locked by means of a screw 24. By turning the sleeve 23 the finger 1 may be so adjusted that it comes to rest in a position immediately behind the needles I, i. e., swings closely behind the same, no matter what the thickness of the needles may be.

The finger I may also be adjusted in height. For this purpose there is provided in a holder 25 screwed on to the arm ID a guide opening 26 for the shaft of the finger I, in which opening the said shaft may be moved up and down, being held in position by a screw 21.

Since the finger I is mounted on the presser rod 9 by means of its rocking arm I 0, finger I and presser foot 4 will be lifted in common. This enables a transverse channel 28 to be provided for the finger I in the foot 4, which channel is covered by the material of the presser foot.

The invention has been described in conjunction with a machine having three needles. There is, however, no restriction to the number of needles employed, and the invention may also be used for all kinds of needle positions, for example for the production of a combined plain stitch and covering seam, in which two covering needles operate behind the centre of the needle rod. In order also in this case to be able to impart the correct position to the finger 1 without necessity for exchanging the entire arm I 0 the holder 25 on the one hand is arranged to be capable of being readily exchanged, whilst on the other hand there are provided additional holders with corresponding lateral displacement of the finger I which holders may be interchanged.

The arrangement may also be such that the finger I is disengaged and maintained in this condition during the normal sewing of the material.

The fixed needle plate tongue which is the loop forming point is shown in Figs. 3 to and this tongue 50 is located in constant spacial disposal to the path of the looper, while the spacing between the point of formation of the loops (needle plate tongue) and the holding finger I is variable, viz., in adaption to the variable thickness of material, which between two pieces of material, is equal to 0. By reason of the variable nature of the holding point .of the needle threads in relation to the point of formation of the loop (needle plate tongue) a longer or shorter length of thread will be drawn through the finger 1 dependent .on the thickness of the article or piece of work, the shorter amount of thread being drawn through when sewing is performed in the absence of material.

Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is:

1. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, and a finger movable together with the said presser foot for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

2. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, and a finger adapted to rock about a verth cal axis and movable together with the said presser foot for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

3. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, and a finger adapted to rock about the rod of the said presser foot and connected therewith in positive fashion for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

4. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, and a finger adapted to be lifted in common with the said presser foot for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

5. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, and a finger movable together with the said presser foot for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, the path of movement of the said finger passing through the said presser foot.

6. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a finger for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, and means for adjusting the plane of the said finger in relation to the said needles.

'7. In a seam covering sewing machine, a plurality of needles, a finger for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, and means for displacing the said finger vertically comprising a finger holder having an opening therein adapted to receive a shaft of the said finger and serving for vertical adjustmentof the finger.

8. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a looper, a finger rocked by the drive of the said looper for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, and an adjustment device for controlling the extent of the rocking movement.

9. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a looper, a transverse shaft driving the said looper, and a finger rocked by the said transverse shaft for firmly holding the needle threads, upon the downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

10. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a looper, a transverse shaft driving the said looper, a finger for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, and an arm on the said transverse shaft for actuating the said finger.

11. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a looper, a finger rocked by the drive of the said looper for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, and means connecting the said looper drive with the said finger, the transmission ratio between the said looper drive and the said finger being variable by varying the point of engagement of the said connecting means.

12. In a seam covering sewing machine, a plurality of needles, a presser foot, a fixed needle plate tongue constituting the point of formation of the loops, a looper, a finger rocked by the drive of the said looper for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam, means for connecting the said looper drive with the said finger, and means for adjusting the said connecting means.

13. A method of performing looping on a multineedle seam covering sewing machine, comprising the step of firmly holding the needle threads, upon each downward movement of the needles, at a point which is variable in relation to the point of formation of the covering seam and lifting the needle threads to perform the looping in dependence upon the thickness of the material and during the upward movement of the needles the needle threads being freed.

14. In a seam covering sewing machine, a plurality of needles, a presser foot, and a finger movable together with the said presser foot for firmly holding the needle threads, upon each downward movement of the said needles, at a point which is variable in relation to the point of formation of the covering seam.

FRITZ EBERT. 

